A variety of rubber products such as hoses, belts rubber rolls and molded goods are widely used for many purposes. With rubber goods, there is continuing need to improve performance by, for example, improving low temperature flexibility, maintaining physical properties when the goods are exposed to heat, and improving oil resistance and ozone resistance. These considerations are of special importance with hydraulic fluid transfer hoses. In that such hoses are used for a multitude of applications, they are produced in great quantities. Accordingly, there is a need to decrease the cost of the rubber compound component of such hoses, as well as to improve the processibility of the rubber compound in both mixing and hose manufacturing steps. As always, it is also desirable to decrease the amount of scrap generated by the manufacturing process.
While accomplishing these ends, it is an important consideration to improve adhesion to metal substrates, such as brass coated wire substrates, which are used for reinforcement. Such an improvement can occur by omitting adhesion promoters from the compound formulation so as to avoid problems in both processing and in the finished product. In addition, there are problems introduced by using processing aids such as waxes and oils which normally interfere with adhesion between the rubber and metal. By minimizing the use of process aids, adhesion between the rubber and metal. By minimizing the use of process aids, adhesion problems can be reduced and the cost of manufacture decreases. In producing hose which has braided wire reinforcement, it is necessary to expose the rubber tubular portion to freezing temperatures. By lowering the freezing temperature, refrigeration costs are reduced. Moreover, with reinforced hose, the tubular portion of the hose which is manufactured from a rubber composition must stiffen prior to braiding. Accordingly, if the tube stiffens more quickly, there is improved dimensional stability during storage prior to braiding so that braiding can be performed more quickly after the rubber tubing has been produced. This lowers inventory and storage costs.
In view of the aforementioned considerations, there is a need for improvements in rubber compounds, which lead to improved hose performance at lower costs. While these considerations are of specific importance relative to hydraulic fluid hose, they are also of considerable importance with respect to other rubber and rubber based products.